HomeMy WebLinkAboutMemo - Mail Packet - 09/03/2024 - Memorandum from Ryan Vincent re: West Nile Virus (WNV) – Weekly UpdateNatural Areas Department
1745 Hoffman Mill Road
PO Box 580, Fort Collins, CO 80522
970-416-2493
rvincent@fcgov.com
CC: Dean Klingner, Community Services Director; Mike Calhoon, Parks Director; Katie Donahue, Natural Areas
Director; Matt Parker, Natural Areas Ecological Stewardship Manager
MEMORANDUM
Date: August 28, 2024
To: Mayor and City Councilmembers
Through: Kelly DiMartino, City Manager
Tyler Marr, Deputy City Manager
From: Ryan Vincent, Natural Areas Sr. Supervisor
Subject: West Nile Virus (WNV) – Weekly Update
BOTTOM LINE
• Based on this week’s data, the Larimer County Department of Health and
Environment (LCDHE) does not recommend spraying for adult mosquitos at this
time.
• However, data shows an amplification of WNV in the NE quadrant. A vector index
(VI) of 0.32 is a high point for the year within this quadrant. This upturn is not due to
higher-than-average abundance rates, but a result of a nearly 4x jump in infection rate
from last week. Staff will continue to monitor this area.
• Seven traps detected WNV this week, up from three last week.
• The 5-trap floating zone with the highest vector index (0.49) was located between
Prospect Road and Harmony Road, and between Timberline Road and I-25.
Current Vector Index Information
Week 34 of 38 VI Threshold: Previous Week VI: Current VI:
FC – Zone NW NA 0.00 0.00
FC – Zone NE NA 0.09 0.32
FC – Zone SE NA 0.01 0.09
FC – Zone SW NA 0.00 0.05
FC – Citywide NA 0.02 0.11
Floating Zone 0.75 0.35 0.49
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BACKGROUND
• Vector Disease Control International (VDCI) reported spraying regularly in the
Town of Timnath and City of Loveland over the past few weeks.
o Timnath sprays an area if a trap catches more than 100 mosquitos.
o Loveland will spray if a trap catches more than 100 mosquitos, or more than 50
culex mosquitos.
• The City of Fort Collins uses abundance data and infection rates to determine if there is
a WNV threat to the community and only sprays for mosquitos that pose a public health
risk, not for nuisance mosquitos.
o Previous City Councils developed this approach to protect the community from
WNV, while protecting the environment by judiciously limiting the amount of
spraying. The City of Fort Collins also recognizes that individuals play a part in
protecting themselves from WNV.
• Citywide public outreach is ongoing and includes social media posts, utility bill inserts,
and other advertising. Staff center outreach information on the “4Ds”:
o Drain standing water.
o Dress in long pants and sleeves to deter biting.
o Defend with EPA-approved repellant.
o Dusk & Dawn – avoid outdoor activities during this high mosquito activity time.
• LCDHE has three confirmed human cases of WNV and continues to monitor potential
new cases. Historically, LCDHE receives the most WNV case reports in August. State
health officials report 13 cases as of Aug. 14, the last date for which data is available.
• City staff, VDCI, and Colorado State University continue to implement preventative WNV
management actions such as larval treatments, trapping, and testing.
• VDCI plans to spray the Willow Springs HOA this week and did not spray any HOAs last
week.
NEXT STEPS
Trapping and testing will continue for four more weeks with staff presenting weekly memos
showing the data.
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